17-hydroxyprogesterone is elevated in patients with congenital adrenal hyperplasia (CAH). CAH is a group of autosomal recessive diseases characterized by a deficiency of cortisol and an excess of ACTH concentration. 17-hydroxyprogesterone is also useful in monitoring cortisol replacement therapy and in evaluating infertility and adrenal and ovarian neoplasms.

Apolipoprotein A1 (APO A1) has been reported to be a better predictor than HDL cholesterol and triglycerides for Coronary Artery Disease (CAD). Low levels of APO A1 in serum are associated with increased risk of CAD. The measurement of APO A1 may be of value in identifying patients with atherosclerosis. Apolipoprotein B (APO B) has been reported to be a more powerful indicator of CAD than total cholesterol or LDL cholesterol in angiographic CAD and in survivors of myocardial infarction. In some patients with CAD, APO B is elevated even in the presence of normal LDL cholesterol.

Measurement of the levels of bilirubin is used in the diagnosis and treatment of liver, hemolytic, hematologic, and metabolic disorders, including hepatitis and gall bladder obstruction. The assessment of direct bilirubin is helpful in the differentiation of hepatic disorders. The increase in total bilirubin associated with obstructive jaundice is primarily due to the direct (conjugated) fraction. Both direct and indirect bilirubin are increased in the serum with hepatitis.

Increased CRP levels are found in inflammatory conditions including: bacterial infection, rheumatic fever, active arthritis, myocardial infarction, malignancies and in the post-operative state. This test cannot detect the relatively small elevations of CRP that are associated with increased cardiovascular risk.

The CA 125 level can provide prognostic information in the follow-up management of patients with ovarian carcinoma. The assay should be used as an adjunctive test in the management of ovarian cancer patients. CA 125 is not recommended as a cancer screening procedure to detect cancer in the general population

CA 15-3 may be useful for monitoring patients with metastatic breast cancer and certain ovarian cancers. The CA 15-3 values from sequential samples have a high correlation with the clinical course in most patients with metastatic breast cancer.

A large percentage of patients with gastrointestinal tumors (such as pancreatic, liver, gastric, colorectal tumors) and some other malignancies have been shown to have elevated serum CA 19-9 levels. Serum CA 19-9 levels may be useful for monitoring disease activity or predicting relapse following treatment. CA 19-9 should not be used as a screening test.

Serum calcium is involved in the regulation of neuromuscular and enzyme activity, bone metabolism and blood coagulation. Calcium blood levels are controlled by a complex interaction of parathyroid hormone, vitamin D, calcitonin and adrenal cortical steroids. Calcium measurements are useful in the diagnosis of parathyroid disease, some bone disorders and chronic renal disease. A low level of calcium may result in tetany.